Insulating material for circuit substrate, and method for manufacturing the same, and metal foil-clad laminate

Abstract

Provided are an insulating material for a circuit substrate, which has excellent dielectric characteristics in a high frequency area, has low coefficients of linear thermal expansion all in a MD direction, a TD direction, and a ZD direction, is easily manufactured and has excellent productivity, and a method for manufacturing the same and a metal foil-clad laminate. An insulating material for a circuit substrate, comprising a laminate having a thermoplastic liquid crystal polymer film and a woven fabric of an inorganic fiber, wherein the thermoplastic liquid crystal polymer film contains an inorganic filler, and the laminate is a dry laminate in which the thermoplastic liquid crystal polymer film and the woven fabric are thermocompression bonded.

1 . An insulating material for a circuit substrate, comprising a laminate having a thermoplastic liquid crystal polymer film and a woven fabric of an inorganic fiber, wherein
 the thermoplastic liquid crystal polymer film contains an inorganic filler, and   the laminate is a dry laminate in which the thermoplastic liquid crystal polymer film and the woven fabric are thermocompression bonded.   
     
     
         2 . The insulating material for a circuit substrate according to  claim 1 , wherein
 the thermoplastic liquid crystal polymer film is a melt-extruded film.   
     
     
         3 . The insulating material for a circuit substrate according to  claim 1 , wherein
 the thermoplastic liquid crystal polymer film is a T-die melt-extruded film.   
     
     
         4 . The insulating material for a circuit substrate according to  claim 1 , wherein
 the inorganic filler contains silica.   
     
     
         5 . The insulating material for a circuit substrate according to  claim 1 , wherein
 the inorganic filler has a median diameter (d50) of 0.01 μm or more and 50 μm or less.   
     
     
         6 . The insulating material for a circuit substrate according to  claim 1 , wherein
 the thermoplastic liquid crystal polymer film contains 1% by mass or more and 45% by mass or less of the inorganic filler based on a total amount of the film.   
     
     
         7 . The insulating material for a circuit substrate according to  claim 1 , wherein
 the woven fabric has a thickness of 10 μm or more and 300 μm or less.   
     
     
         8 . The insulating material for a circuit substrate according to  claim 1 , wherein
 the woven fabric of the inorganic fiber is a glass cloth.   
     
     
         9 . The insulating material for a circuit substrate according to  claim 1 , wherein
 an average coefficient of linear thermal expansion at 23 to 200° C., as measured by a TMA method according to JIS K7197, is 5 ppm/K or more and 25 ppm/K or less in an in-plane direction and 10 ppm/K or more and 100 ppm/K or less in a thickness direction.   
     
     
         10 . The insulating material for a circuit substrate according to  claim 1 , wherein
 a relative dielectric constant ε r  at 36 GHz, as measured by a cavity resonator perturbation method according to JIS K6471, is 3.0 or more and 3.7 or less.   
     
     
         11 . The insulating material for a circuit substrate according to  claim 1 , wherein
 a dielectric loss tangent tan δ at 36 GHz, as measured by a cavity resonator perturbation method according to JIS K6471, is 0.0010 or more and 0.0050 or less.   
     
     
         12 . A method for manufacturing an insulating material for a circuit substrate, comprising
 a step of preparing a thermoplastic liquid crystal polymer film containing an inorganic filler,   a step of preparing a woven fabric of an inorganic fiber, and   a step of laminating the thermoplastic liquid crystal polymer film and the woven fabric, and heating and pressurizing the resultant, to thereby form a dry laminate in which the thermoplastic liquid crystal polymer film and the woven fabric are thermocompression bonded.   
     
     
         13 . The method for manufacturing an insulating material for a circuit substrate according to  claim 12 , wherein
 the step of preparing the thermoplastic liquid crystal polymer film comprises   a composition preparation step of preparing a resin composition containing the thermoplastic liquid crystal polymer and the inorganic filler, and   a film formation step of molding the resin composition to thereby form the thermoplastic liquid crystal polymer film containing the inorganic filler.   
     
     
         14 . A metal foil-clad laminate comprising
 the insulating material for a circuit substrate according to  claim 1 , and a metal foil(s) provided on one surface and/or both surfaces of the insulating material for a circuit substrate.